A phenotype for reading?

In Jonathan Franzen's essay, "Why Bother?" (Harper's, '96), he talks about linguist and MacArthur Fellow Shirley Brice Heath and her research on the reading habits of Americans. Her conclusions led her to believe there are are two kinds of readers:

"social-isolate" readers: surprise--socially isolated (but this, as opposed to antisocial); sublimated this pain into investing in imaginary worlds; felt connected to the authors

I have to say this rings true. Plus, I'm a sucker for dividing large groups into two categories! (I almost collect them: "You're a giver or you're a taker"; "You're a cook or you're a baker"; "You're an Elvis person or you're a Beatles person). I'd have to say I'm a social-isolate reader. My parents were pretty well occupied with the exigencies of raising strange and demanding children to carve out time alone for reading (my mother's favorite book was Five Minutes' Peace). Interested to hear what kind you are, or if you think the two camps should be recalibrated...